The present invention relates to pharmaceutical preparations in the form of stable ethanolic solutions of active substances for producing propellant-free aerosols.
In the last 20 years, the use of metering aerosols has become an established component of the treatment of obstructive lung diseases, particularly asthma. Usually, fluorochlorohydrocarbons have been used as propellant gases. Since the ozone-damaging potential of these propellant gases was recognised, more and more efforts have been made to develop alternatives. One alternative is the development of nebulisers in which aqueous solutions of pharmacologically-active substances are sprayed under high pressure so as to produce a mist of inhalable particles. The advantage of these nebulisers is that there is no need to use any propellant gases whatsoever.
Some nebulisers are described, for example, in PCT Patent Application WO091/14468, the contents of which are referred to hereinafter. In the nebulisers described therein, solutions of defined volumes containing active substances are sprayed, using high pressures through small nozzles so as to produce inhalable aerosols with a preferred particle size of between 1 and 10, preferably between 2 and 5 micrometers.
Hitherto, it has been assumed that, with conventional metering aerosols containing propellant gas, the optimum level of lung-bound particles is obtained in the aerosol. It has now been found, surprisingly, that by using ethanolic active substance solutions in combination with, for example, the above-mentioned nebulisers it is possible to generate a significantly better spectrum of inhalable particles than is usually the case with metering aerosols which contain propellant gas.
Suitable solvents for the pharmaceutical preparation within the scope of the present inventions are solutions containing at least 70% (v/v) of ethanol; solutions containing at least 85% (v/v) are preferred whilst solutions having an ethanol content of more than 95% (v/v) are particularly preferred. The concentration is given in percent by volume (v/v), the remainder being water. Most particularly preferred is ethanol which already contains small amounts of water, e.g. 96% ethanol, so that it is no longer hygroscopic and evaporates azeotropically.
Apart from water, the solvent may include other cosolvents and the pharmaceutical preparation may also contain flavourings and other pharmacological excipients. Examples of cosolvents are those which contain hydroxyl groups or other polar groups, e.g. alcohols, especially isopropyl alcohol, glycols, particularly propylene glycol, polyethylene glycol, polypropylene glycol, glycol ether, glycerol, polyoxyethylene alcohols and esters of polyoxyethylene fatty acids. Cosolvents are suitable for increasing the solubility of the excipients and possibly the active substances.
The proportion of dissolved pharmaceutical substance in the finished pharmaceutical preparation is between 0.001 and 5%, preferably between 0.05 and 3%, most particularly 0.01 to 2%, where the figures refer to the percentage by weight. The maximum concentration of pharmaceutical substance depends on the solubility in the solvent and on the dosage required to achieve the desired therapeutic effect.
As pharmaceutically active agent in the new preparations, it is possible to use any substances which are suitable for administration by inhalation and which are soluble in the solvent specified. These may include, in particular, betamimetics, anticholinergics, antiallergics, PAF-antagonists and particularly steroids and combinations of active substances thereof.
The following are mentioned specifically by way of example:
Tiotropium bromide, 3-[(hydroxydi-2-thienylacetyl)oxy]-8,8-dimethyl-8-azoniabicyclo[3,2,1]oct-6-en-bromide
As betamimetics:
1-(2-fluoro-4-hydroxyphenyl)-2-[4-(1-benzimidazolyl)-2-methyl-2- butylamino]ethanol,
erythro-5xe2x80x2-hydroxy-8xe2x80x2-(1-hydroxy-2-isopropylaminobutyl)-2H-1,4-benzoxazin-3-(4H)-one,
1-(4-amino-3-chloro-5-trifluoromethylphenyl)-2-tert.-butyl-amino)ethanol,
1-(4-ethoxycarbonylamino-3-cyano-5-fluorophenyl)-2-(tert.-butylamino)ethanol.
As anticholinergics:
Ipratropium bromide
Oxitropium bromide
Trospium chloride
N-xcex2-fluorethylnortropine benzilate methobromide
As steroids:
Budesonide
Beclomethasone (or the 17,21-dipropionate)
Dexamethasone-21-isonicotinate
Flunisolide
As antiallergics:
Disodium cromoglycate
Nedocromil
Epinastin
As PAF-antagonists:
WEB 2086 (4-(2-chlorophenyl)-9-methyl-2-[3-(4-morpholinyl)-3-propanon-1-yl]-6H-thieno-[3,2-f][1,2,4]-triazolo[4,3-a][1,4]diazepine)
WEB 2170 (6-(2-chlorophenyl)-8,9-dihydro-1-methyl-8-[(4-morpholinyl)carbonyl]-4H,7H-cyclopenta[4,5]thieno-[3,2-f][1,2,4]triazolo[4,3-a][1,4]diazepine)
The pharmaceutical preparations according to the invention may contain other excipients such as soya lecithin or surface-active substances.
Surprisingly, it has also been found that the addition of an organic or inorganic acid, preferably in conjunction with a complex forming agent, leads to an improvement in the stability (shelf life) of steroid-containing preparations. This has been found particularly useful for pharmaceutical preparations which contain as active substance Flunisolide or the hydrate or hemihydrate thereof or Budenoside, and which contain ethanol as solvent.
Examples of inorganic acids include, for example: hydrochloric acid, sulphuric acid or phosphoric acid; examples of organic acids include ascorbic acid, malic acid, citric acid, tartaric acid, maleic acid, succinic acid, fumaric acid, acetic acid, formic acid, propionic acid, etc.
The amount of acid in the finished pharmaceutical preparation is in every case selected so that the pH of the solution is between 2.0 and 7.0, especially between 3.0 and 4.0.
In a preferred embodiment, the pharmaceutical preparation also contains a complex forming agent. Examples of complex forming agents include EDTA, citric acid, nitrilo triacetic acid and the salts thereof. The quantity of complex forming agent is between 0.1 and 3 mg/100 ml, preferably between 0.2 and 2 mg/100 ml, particularly between 0.9 and 1.1 mg/100 ml, based on the finished pharmaceutical preparation.
The preferred complex forming agent is EDTA (ethylene diamine tetraacetic acid or a salt thereof, such as the disodium salt). A preferred pharmaceutical preparation according to the present invention contains 1.667% Flunisolide in the ethanol (96% v/v) as solvent, which contains 0.01% (v/v) EDTA as complex forming agent and is adjusted by the addition of acid to a pH of between 3.0 and 4.0.
Examples of steroids which may be used as an active substance in the pharmaceutical preparation according to the invention are:
9xcex1-chloro-6xcex1-fluoro-11xcex2,17xcex1-dihydroxy-16xcex1-methyl-3-oxo-1,4-androstadiene-17xcex2-carboxylic acid methylester-17-propionate.
Table 1 shows a comparison of a deposition study which was carried out on the one hand with a standard commercial metering aerosol Inhacort(copyright) (Flunisolide, dichloromathane, trichlorofluoromethane, cryofluoran, sorbitane triolate)=MDI, and on the other hand with the pharmaceutical preparation according to the invention containing Flunisolide in 96% (v/v) ethanol, which was carried out with a nebuliser as in the above-mentioned PCT Application WO 91/14468 (BINEB(copyright); technical data: volume of drug preparation administered 15 xcexcl, pressure approx. 300 bar, 2 jets squeezed out of two nozzle openings measuring 5xc3x978 xcexcm).
The Table clearly shows the advantage of the pharmaceutical preparation according to the invention which was administered with the nebuliser described.